[Feature] Add UnaryExpression and Negate

[matthew-mccall]

This PR adds UnaryExpression. An abstract node for expressions with a single operand such as negation, square roots, etc.

This PR also adds the Negate node, a convenience node to make tree insertion and balancing easier, for instance dealing with Add. This addresses #12.

[github-actions]

Filename                               Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
src/Expression.cpp                         132                13    90.15%          19                 4    78.95%         252                26    89.68%         102                15    85.29%
src/Imaginary.cpp                           10                 4    60.00%           4                 1    75.00%          12                 3    75.00%           4                 2    50.00%
src/Log.cpp                                 44                10    77.27%           6                 3    50.00%          56                17    69.64%          28                 8    71.43%
src/Real.cpp                                14                 1    92.86%           6                 0   100.00%          17                 0   100.00%           8                 1    87.50%
src/Undefined.cpp                            9                 9     0.00%           3                 3     0.00%           9                 9     0.00%           4                 4     0.00%
src/Exponent.cpp                            81                26    67.90%          10                 6    40.00%         143                72    49.65%          54                19    64.81%
src/Add.cpp                                148                43    70.95%          10                 1    90.00%         229                58    74.67%         110                42    61.82%
src/Divide.cpp                             170                62    63.53%          10                 2    80.00%         255                86    66.27%         132                60    54.55%
src/Subtract.cpp                            61                20    67.21%          10                 3    70.00%         118                31    73.73%          38                18    52.63%
src/Multiply.cpp                           171                29    83.04%          10                 1    90.00%         276                63    77.17%         132                35    73.48%
src/Variable.cpp                            14                 4    71.43%           6                 1    83.33%          17                 3    82.35%           8                 2    75.00%
include/Oasis/Log.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Divide.hpp                     6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Subtract.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Add.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/LeafExpression.hpp             4                 0   100.00%           4                 0   100.00%          12                 0   100.00%           0                 0         -
include/Oasis/BinaryExpression.hpp         183                12    93.44%          41                 0   100.00%         395                19    95.19%         110                43    60.91%
include/Oasis/Expression.hpp                 7                 1    85.71%           7                 1    85.71%          19                 3    84.21%           0                 0         -
include/Oasis/Imaginary.hpp                  2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
include/Oasis/Exponent.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Multiply.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Undefined.hpp                  3                 1    66.67%           3                 1    66.67%           3                 1    66.67%           0                 0         -
include/Oasis/UnaryExpression.hpp           20                15    25.00%          12                 9    25.00%          47                34    27.66%           4                 4     0.00%
include/Oasis/Negate.hpp                     5                 3    40.00%           5                 3    40.00%          21                12    42.86%           0                 0         -
include/Oasis/Variable.hpp                   1                 0   100.00%           1                 0   100.00%           1                 0   100.00%           0                 0         -
include/Oasis/Real.hpp                       2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                     1117               259    76.81%         207                45    78.26%        1946               455    76.62%         734               253    65.53%

Generated by llvm-cov -- llvm version 17.0.6

[github-actions]

Filename                               Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
src/Expression.cpp                         132                13    90.15%          19                 4    78.95%         252                26    89.68%         102                15    85.29%
src/Imaginary.cpp                           10                 4    60.00%           4                 1    75.00%          12                 3    75.00%           4                 2    50.00%
src/Log.cpp                                 44                10    77.27%           6                 3    50.00%          56                17    69.64%          28                 8    71.43%
src/Real.cpp                                14                 1    92.86%           6                 0   100.00%          17                 0   100.00%           8                 1    87.50%
src/Undefined.cpp                            9                 9     0.00%           3                 3     0.00%           9                 9     0.00%           4                 4     0.00%
src/Exponent.cpp                            81                26    67.90%          10                 6    40.00%         143                72    49.65%          54                19    64.81%
src/Add.cpp                                148                43    70.95%          10                 1    90.00%         229                58    74.67%         110                42    61.82%
src/Divide.cpp                             170                62    63.53%          10                 2    80.00%         255                86    66.27%         132                60    54.55%
src/Subtract.cpp                            61                20    67.21%          10                 3    70.00%         118                31    73.73%          38                18    52.63%
src/Multiply.cpp                           171                29    83.04%          10                 1    90.00%         276                63    77.17%         132                35    73.48%
src/Variable.cpp                            14                 4    71.43%           6                 1    83.33%          17                 3    82.35%           8                 2    75.00%
include/Oasis/Log.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Divide.hpp                     6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Subtract.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Add.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/LeafExpression.hpp             4                 0   100.00%           4                 0   100.00%          12                 0   100.00%           0                 0         -
include/Oasis/BinaryExpression.hpp         183                12    93.44%          41                 0   100.00%         395                19    95.19%         110                43    60.91%
include/Oasis/Expression.hpp                 7                 1    85.71%           7                 1    85.71%          19                 3    84.21%           0                 0         -
include/Oasis/Imaginary.hpp                  2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
include/Oasis/Exponent.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Multiply.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Undefined.hpp                  3                 1    66.67%           3                 1    66.67%           3                 1    66.67%           0                 0         -
include/Oasis/UnaryExpression.hpp           20                15    25.00%          12                 9    25.00%          47                34    27.66%           4                 4     0.00%
include/Oasis/Negate.hpp                     5                 3    40.00%           5                 3    40.00%          21                12    42.86%           0                 0         -
include/Oasis/Variable.hpp                   1                 0   100.00%           1                 0   100.00%           1                 0   100.00%           0                 0         -
include/Oasis/Real.hpp                       2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                     1117               259    76.81%         207                45    78.26%        1946               455    76.62%         734               253    65.53%

Generated by llvm-cov -- llvm version 17.0.6

[github-actions]

Filename                               Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
src/Expression.cpp                         132                13    90.15%          19                 4    78.95%         252                26    89.68%         102                15    85.29%
src/Imaginary.cpp                           10                 4    60.00%           4                 1    75.00%          12                 3    75.00%           4                 2    50.00%
src/Log.cpp                                 44                10    77.27%           6                 3    50.00%          56                17    69.64%          28                 8    71.43%
src/Real.cpp                                14                 1    92.86%           6                 0   100.00%          17                 0   100.00%           8                 1    87.50%
src/Undefined.cpp                            9                 9     0.00%           3                 3     0.00%           9                 9     0.00%           4                 4     0.00%
src/Exponent.cpp                            81                26    67.90%          10                 6    40.00%         143                72    49.65%          54                19    64.81%
src/Add.cpp                                148                43    70.95%          10                 1    90.00%         229                58    74.67%         110                42    61.82%
src/Divide.cpp                             170                62    63.53%          10                 2    80.00%         255                86    66.27%         132                60    54.55%
src/Subtract.cpp                            61                20    67.21%          10                 3    70.00%         118                31    73.73%          38                18    52.63%
src/Multiply.cpp                           171                29    83.04%          10                 1    90.00%         276                63    77.17%         132                35    73.48%
src/Variable.cpp                            14                 4    71.43%           6                 1    83.33%          17                 3    82.35%           8                 2    75.00%
include/Oasis/Log.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Divide.hpp                     6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Subtract.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Add.hpp                        6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/LeafExpression.hpp             4                 0   100.00%           4                 0   100.00%          12                 0   100.00%           0                 0         -
include/Oasis/BinaryExpression.hpp         183                12    93.44%          41                 0   100.00%         395                19    95.19%         110                43    60.91%
include/Oasis/Expression.hpp                 7                 1    85.71%           7                 1    85.71%          19                 3    84.21%           0                 0         -
include/Oasis/Imaginary.hpp                  2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
include/Oasis/Exponent.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Multiply.hpp                   6                 1    83.33%           6                 1    83.33%          10                 3    70.00%           0                 0         -
include/Oasis/Undefined.hpp                  3                 1    66.67%           3                 1    66.67%           3                 1    66.67%           0                 0         -
include/Oasis/UnaryExpression.hpp           20                15    25.00%          12                 9    25.00%          47                34    27.66%           4                 4     0.00%
include/Oasis/Negate.hpp                     5                 3    40.00%           5                 3    40.00%          21                12    42.86%           0                 0         -
include/Oasis/Variable.hpp                   1                 0   100.00%           1                 0   100.00%           1                 0   100.00%           0                 0         -
include/Oasis/Real.hpp                       2                 0   100.00%           2                 0   100.00%           2                 0   100.00%           0                 0         -
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                     1117               259    76.81%         207                45    78.26%        1946               455    76.62%         734               253    65.53%

Generated by llvm-cov -- llvm version 17.0.6